?? i2c_master_byte_ctrl.v.txt
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/////////////////////////////////////////////////////////////////////
//// ////
//// WISHBONE rev.B2 compliant I2C Master byte-controller ////
//// ////
//// ////
//// Author: Richard Herveille ////
//// richard@asics.ws ////
//// www.asics.ws ////
//// ////
//// Downloaded from: http://www.opencores.org/projects/i2c/ ////
//// ////
/////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2001 Richard Herveille ////
//// richard@asics.ws ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer.////
//// ////
//// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR ////
//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ////
//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ////
//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE ////
//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR ////
//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF ////
//// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ////
//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT ////
//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ////
//// POSSIBILITY OF SUCH DAMAGE. ////
//// ////
/////////////////////////////////////////////////////////////////////
// CVS Log
//
// $Id: i2c_master_byte_ctrl.v,v 1.7 2004/02/18 11:40:46 rherveille Exp $
//
// $Date: 2004/02/18 11:40:46 $
// $Revision: 1.7 $
// $Author: rherveille $
// $Locker: $
// $State: Exp $
//
// Change History:
// $Log: i2c_master_byte_ctrl.v,v $
// Revision 1.7 2004/02/18 11:40:46 rherveille
// Fixed a potential bug in the statemachine. During a 'stop' 2 cmd_ack signals were generated. Possibly canceling a new start command.
//
// Revision 1.6 2003/08/09 07:01:33 rherveille
// Fixed a bug in the Arbitration Lost generation caused by delay on the (external) sda line.
// Fixed a potential bug in the byte controller's host-acknowledge generation.
//
// Revision 1.5 2002/12/26 15:02:32 rherveille
// Core is now a Multimaster I2C controller
//
// Revision 1.4 2002/11/30 22:24:40 rherveille
// Cleaned up code
//
// Revision 1.3 2001/11/05 11:59:25 rherveille
// Fixed wb_ack_o generation bug.
// Fixed bug in the byte_controller statemachine.
// Added headers.
//
// synopsys translate_off
`include "timescale.v"
// synopsys translate_on
`include "i2c_master_defines.v"
module i2c_master_byte_ctrl (
clk, rst, nReset, ena, clk_cnt, start, stop, read, write, ack_in, din,
cmd_ack, ack_out, dout, i2c_busy, i2c_al, scl_i, scl_o, scl_oen, sda_i, sda_o, sda_oen );
//
// inputs & outputs
//
input clk; // master clock
input rst; // synchronous active high reset
input nReset; // asynchronous active low reset
input ena; // core enable signal
input [15:0] clk_cnt; // 4x SCL
// control inputs
input start;
input stop;
input read;
input write;
input ack_in;
input [7:0] din;
// status outputs
output cmd_ack;
reg cmd_ack;
output ack_out;
reg ack_out;
output i2c_busy;
output i2c_al;
output [7:0] dout;
// I2C signals
input scl_i;
output scl_o;
output scl_oen;
input sda_i;
output sda_o;
output sda_oen;
//
// Variable declarations
//
// statemachine
parameter [4:0] ST_IDLE = 5'b0_0000;
parameter [4:0] ST_START = 5'b0_0001;
parameter [4:0] ST_READ = 5'b0_0010;
parameter [4:0] ST_WRITE = 5'b0_0100;
parameter [4:0] ST_ACK = 5'b0_1000;
parameter [4:0] ST_STOP = 5'b1_0000;
// signals for bit_controller
reg [3:0] core_cmd;
reg core_txd;
wire core_ack, core_rxd;
// signals for shift register
reg [7:0] sr; //8bit shift register
reg shift, ld;
// signals for state machine
wire go;
reg [2:0] dcnt;
wire cnt_done;
//
// Module body
//
// hookup bit_controller
i2c_master_bit_ctrl bit_controller (
.clk ( clk ),
.rst ( rst ),
.nReset ( nReset ),
.ena ( ena ),
.clk_cnt ( clk_cnt ),
.cmd ( core_cmd ),
.cmd_ack ( core_ack ),
.busy ( i2c_busy ),
.al ( i2c_al ),
.din ( core_txd ),
.dout ( core_rxd ),
.scl_i ( scl_i ),
.scl_o ( scl_o ),
.scl_oen ( scl_oen ),
.sda_i ( sda_i ),
.sda_o ( sda_o ),
.sda_oen ( sda_oen )
);
// generate go-signal
assign go = (read | write | stop) & ~cmd_ack;
// assign dout output to shift-register
assign dout = sr;
// generate shift register
always @(posedge clk or negedge nReset)
if (!nReset)
sr <= #1 8'h0;
else if (rst)
sr <= #1 8'h0;
else if (ld)
sr <= #1 din;
else if (shift)
sr <= #1 {sr[6:0], core_rxd};
// generate counter
always @(posedge clk or negedge nReset)
if (!nReset)
dcnt <= #1 3'h0;
else if (rst)
dcnt <= #1 3'h0;
else if (ld)
dcnt <= #1 3'h7;
else if (shift)
dcnt <= #1 dcnt - 3'h1;
assign cnt_done = ~(|dcnt);
//
// state machine
//
reg [4:0] c_state; // synopsis enum_state
always @(posedge clk or negedge nReset)
if (!nReset)
begin
core_cmd <= #1 `I2C_CMD_NOP;
core_txd <= #1 1'b0;
shift <= #1 1'b0;
ld <= #1 1'b0;
cmd_ack <= #1 1'b0;
c_state <= #1 ST_IDLE;
ack_out <= #1 1'b0;
end
else if (rst | i2c_al)
begin
core_cmd <= #1 `I2C_CMD_NOP;
core_txd <= #1 1'b0;
shift <= #1 1'b0;
ld <= #1 1'b0;
cmd_ack <= #1 1'b0;
c_state <= #1 ST_IDLE;
ack_out <= #1 1'b0;
end
else
begin
// initially reset all signals
core_txd <= #1 sr[7];
shift <= #1 1'b0;
ld <= #1 1'b0;
cmd_ack <= #1 1'b0;
case (c_state) // synopsys full_case parallel_case
ST_IDLE:
if (go)
begin
if (start)
begin
c_state <= #1 ST_START;
core_cmd <= #1 `I2C_CMD_START;
end
else if (read)
begin
c_state <= #1 ST_READ;
core_cmd <= #1 `I2C_CMD_READ;
end
else if (write)
begin
c_state <= #1 ST_WRITE;
core_cmd <= #1 `I2C_CMD_WRITE;
end
else // stop
begin
c_state <= #1 ST_STOP;
core_cmd <= #1 `I2C_CMD_STOP;
end
ld <= #1 1'b1;
end
ST_START:
if (core_ack)
begin
if (read)
begin
c_state <= #1 ST_READ;
core_cmd <= #1 `I2C_CMD_READ;
end
else
begin
c_state <= #1 ST_WRITE;
core_cmd <= #1 `I2C_CMD_WRITE;
end
ld <= #1 1'b1;
end
ST_WRITE:
if (core_ack)
if (cnt_done)
begin
c_state <= #1 ST_ACK;
core_cmd <= #1 `I2C_CMD_READ;
end
else
begin
c_state <= #1 ST_WRITE; // stay in same state
core_cmd <= #1 `I2C_CMD_WRITE; // write next bit
shift <= #1 1'b1;
end
ST_READ:
if (core_ack)
begin
if (cnt_done)
begin
c_state <= #1 ST_ACK;
core_cmd <= #1 `I2C_CMD_WRITE;
end
else
begin
c_state <= #1 ST_READ; // stay in same state
core_cmd <= #1 `I2C_CMD_READ; // read next bit
end
shift <= #1 1'b1;
core_txd <= #1 ack_in;
end
ST_ACK:
if (core_ack)
begin
if (stop)
begin
c_state <= #1 ST_STOP;
core_cmd <= #1 `I2C_CMD_STOP;
end
else
begin
c_state <= #1 ST_IDLE;
core_cmd <= #1 `I2C_CMD_NOP;
// generate command acknowledge signal
cmd_ack <= #1 1'b1;
end
// assign ack_out output to bit_controller_rxd (contains last received bit)
ack_out <= #1 core_rxd;
core_txd <= #1 1'b1;
end
else
core_txd <= #1 ack_in;
ST_STOP:
if (core_ack)
begin
c_state <= #1 ST_IDLE;
core_cmd <= #1 `I2C_CMD_NOP;
// generate command acknowledge signal
cmd_ack <= #1 1'b1;
end
endcase
end
endmodule
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